Add exclude option

[Ndpnt]

Add exclude option to avoid prefixing some selectors

Usage:

var css = '.a {} \nhtml{} \n.b{}'

var prefix = require('postcss-prefix-selector')

var out = postcss().use(prefix({
  prefix: '.some-selector ', // <--- notice the traililng space!
  exclude: ['html', '.b']
})).process(css).css

console.log(out) // only .a selector will be prefixed

Bump version to 1.2.0

[coveralls]

Coverage remained the same at 100.0% when pulling 9d7f3fd on Ndpnt:add-exclude-option into 20f4162 on jonathanong:master.

[jonathanong]

added you as a collab. what's your npm name?

[Ndpnt]

Thanks. My npm name is ndpnt

[jonathanong]

added

[Ndpnt]

Thank you for adding me as a collab :)

[Ndpnt]

Hey !
Just to be sure, you added me as a collaborator to let me merge this PR and publish the new version on npm?
Do you have usual contributing conventions like code reviews, tests, semver, doc…?

[jonathanong]

Denver and update docs :)

[valentin-radulescu-hs]

👍 on getting this merged

[valentin-radulescu-hs]

@jonathanong Can you add me on npm so I can publish the update? Username is valentin-radulescu-hs